Tomorrow is the 75th anniversary of an achievement that has shaped the world in which we live: the jet engine. On April 12, 1937, Sir Frank Whittle’s nearly ten-year quest to build a working gas turbine engine culminated with a test run of the eponymous WU (for Whittle Unit). During that first lab experiment, the minutiae of WU turbine’s operation were thus: rotated at 8,000 rpm, sucked in 13,000 cubic feet of air per minute, and burned four gallons of fuel per minute. It also nearly destroyed itself as the turbine spun out of control, flames escaped from every crevice, and Whittle’s lab mates ducked for cover. Whittle shut off the fuel valve and waited for the shrieking machine to slow to a halt.
Whittle first joined the Royal Air Force (RAF) as a sixteen year old and was accepted into a program that trained mechanics. Before long, his mechanical aptitude and mathematical prowess asserted itself, and he was selected for training at Cranwell, the RAF’s officer’s candidate school. At Cranwell, while working on a thesis that addressed high-speed, high-altitude flight, he first had the insight that piston engines and propellers were inadequate to the future of flight that he envisaged. As a direct outcome of that thesis, Whittle applied for and was granted a patent for jet engines in 1930.
The computer scientist Alan Kay has said, “The best way to predict the future is to invent it.” Whittle’s patent is a perfect model of that quote in that, in addition to setting out the basic parameters for the jet engine, he also described the techniques that underpin afterburners and thrust vectoring. More importantly, his patent and design reduced the complex allocation of moving parts that exist in a piston engine to a single spinning shaft with a compressor or one end and a turbine wheel on the opposite end.
Like many stories of technical breakthroughs, Whittle’s path to the jet engine was not trouble free. He faced fierce skepticism from his RAF colleagues, financial difficulties (Whittle’s patent expired when he could not afford the renewal fee of £5), and the engineering challenges associated with doing something wholly original. In the end, it was Whittle’s design—the W.1 engine—that thrust the first British jet airplane into the sky on May 15, 1941.
However, by the time that Whittle’s engine successfully flew in the British Gloster E28/39, a German jet, the Heinkel 178 with an engine designed by Hans von Ohain, had flown two years previous. Though Whittle produced the first jet engine, the German military produced the first successful jet aircraft. After the war, both Whittle and von Ohain would ultimately come to reside in the United States (von Ohain in 1947 and Whittle in 1976). See more about the two engineers HERE.
As an aside about experimental aircraft and test pilots: in April 1941, the Gloster E28/39 was being put through a series of taxiing tests using a non-airworthy engine, the W.1X. Much like Howard Hughes’s famous 1947 taxiing test of the Spruce Goose, where he “accidentally” lifted off to an altitude of 70 feet above the ocean near Long Beach, the non-airworthy version of the W.1X took to the skies in a series of six- to ten-feet-high hops above its grass runaway. After all, if you put a pilot in something with wings, what do you expect to happen? NASA knew how pilots behaved. The lunar module for Apollo 10 had just enough fuel to carry out its intended mission of almost landing on the Moon, and it’s been suggested that NASA management didn’t authorize a full fuel load out of fear that crew might make an unscheduled “emergency” landing. NASA higher-ups removed a temptation that earlier test pilots hadn’t been able to resist, the urge to be the first.
A return to today’s main topic: Whittle’s engineering legacy has had far reaching consequences. Gas turbines provide the power for an enormous range of vehicles (tanks and ships in addition to aircraft), and they are also used to generate electrical power. Globally, the size of the civilian aerospace market is $275B. In the United States alone, the value of the airline industry was $180B in 2011.
As soon as you finish reading this post, go outside and look up into the sky. The FAA reports that at any given time, there are as many as 7000 aircraft in the sky. As we write this post, Flightaware, a lovely website for aviation geeks, is reporting that there are 6394 planes in the sky. Using Flightaware’s type tracking feature even allows you to see the types of the airplanes that are flying. A quick glance at that tracking page makes it obvious that the vast majority of the aircraft flying above our heads are powered by some form of jet engine.